288 LHE CEPHALOPODA 
structure being largely composed of an extension of the sheaths 
of the tentacles in question. On the ventral side an extensive 
part of the internal surface of the muscular ring is laminated, 
Fia. 255. 
Male (upper) and female (lower) specimens of Nautilus pompilius, as seen in the expanded 
condition ; oral view, showing the disposition of the tentaculiferous lobes and the differences 
between the two sexes. a, the shell; b, the outer ring-like expansion or annular lobe of the 
cireumoral mass of the foot, dorsally forming the hood ; ¢, the right and left inner lobes of the 
foot, each carrying twelve tentacles in the female, in the male divided into p, the ‘‘ spadix ” 
(hectocotylus) on the left side, and q, the ‘‘anti-spadix,” a group of four tentacles, on the right 
side ; d, the inner inferior lobe of the foot (reduced in the male to a paired group of lamellae) ; 
e, the buccal cone, fringing the jaws with a series of minute papillae; f, the tentacles of the 
outer lobe, projecting from their sheaths ; g, the two most posterior tentacles, belonging to the 
hood ; i, superior ophthalmic tentacle; k, inferior ophthalmic tentacle; l, eye; m, paired 
laminated organ on each side of the base of the inner inferior lobe of the female; m, olfactory 
lamellae upon the inner inferior lobe, in the female; 0, the funnel; p, the spadix (in the male) 
or hectocotylised portion of the left inner lobe of the foot, representing four modified tentacles ; 
q, the antispadix (in the male), being four of the twelve tentacles of the right inner lobe, isolated 
from the remaining eight. (After Lankester.) 
